a. Field of the Invention
The present invention relates to a method for melting the raw materials for preparing glass, and particularly it is intended to provide a method for melting the raw materials for glass which renders it possible not only to reduce the fuel consumption by enhancing the melting efficiency but also to effect uniform melting.
B. Description of the Prior Art
In the industrial manufacturing of flat glass, container glass, glass fiber, etc., a large-sized furnace, or a tank furnace, is usually employed, and the melting of the raw materials for glass is effected by a process comprising piling up the raw materials, to wit, quartz sand, soda ash, dolomite, etc. supplied in proportion to the amount of glass to be drawn out of the furnace, on molten glass and melting said raw materials by conductive heat from the molten glass together with the radiant heat of flames.
However, in the case of melting the raw materials for glass by the conventional method as above, the thermal efficiency is very low. This is mainly due to the fact that, according to the conventional method wherein the surface portion of the raw materials placed on the molten glass is melted by means of the radiant heat from flames while the bottom portion thereof is melted by means of the conductive heat from the molten glass successively and the thus melted raw materials flow into the molten glass, the surface layer portion of raw materials is vitrified easily by virtue of the radiant heat of the flames, but the thus vitrified surface layer portion of the raw materials impedes the conduction of the radiant heat of the flames to the underlying layer of raw materials. In order to effect the melting sufficiently by heating with flames, the upper layer of the raw materials for glass must be melted with flames and rapidly flow into the molten glass, but, as a matter of fact, the melt of the thus melted raw materials is of such a high viscosity that its rapid flowing into the molten glass is infeasible and, accordingly, a tremendous amount of fuel is required for the melting of raw materials for glass.
Moreover, in the conventional method, the raw materials for glass melted with the heat conducted from the molten glass are supposed to flow into the molten glass by virtue of natural convection of the molten glass. However, the speed of said convection is so low that the melted raw materials cannot flow into the molten glass rapidly, and this also constitutes a cause of the lowering of the thermal efficiency of the method.
As discussed in the foregoing, it is impossible to operate a glass tank furnace at a high thermal efficiency by the melting method in the prior art.